Technical Field
The present invention relates to a system and method for avoiding mobile relay interference to a primary system on an authorized frequency spectrum.
Related Art
With development of mobile networks, carrier spectrums of existing mobile networks not only carry voice, short message and other traditional mobile services, but also are responsible for transmitting a large amount of data on the Internet, which causes carrier spectrum resources of the mobile networks to become more and more scarce, and in order to alleviate the spectrum resources of the mobile networks, transmitting mobile services by using the existing spectrums has become a hotspot. A cognitive radio (CR) technology can greatly increase spectrum utilization by allowing unauthorized users to have the chance to use spectrum resources of a primary system. In order to solve spectrum resource shortage problems of LTE systems and some problems of low spectrum utilization of other authorized frequency bands, the prior art puts forward a spectrum authorization scheme, and the scheme is called “authorized shared access” (ASA). The ASA scheme is based on authorization models of spectrum rights, to allow a secondary LTE system to use the CR technology (geographic location database, cognition and so on) to share spectrum resources with the existing primary system.
Therefore, in order to be capable of achieving resource sharing and noninterference of authorized frequency spectrums, a base station near the primary system must satisfy: the range covered by the base station must have no intersection with the range protected during transmission of the primary system, meanwhile, in order to ensure that a mobile relay within the coverage range of the base station does not interfere with operation of the primary system, it is required that a carrier frequency used by the mobile relay cannot interfere with normal operation of the primary system. The manner of making the mobile relay not interfere with the primary system is generally as follows: changing transmitting power of the mobile relay or changing a frequency used by the mobile relay. However, as the primary system does not transmit a signal at a fixed frequency during operation and the mobile relay may cause harmful interference to the primary system due to a change of its position, how to real-time change maximum transmitting power or carrier frequency of the mobile relay according to transmitting power of the primary system and the geographic position of the mobile relay to avoid harmful interference to the primary system is a problem to be solved by persons skilled in the art.